The present invention is directed toward spirocyclic benzopyran imidazolines of Formula shown below, and their use for treatment of hypertension, alopecia, and erectile dysfunction. The subject compounds act by opening cell membrane potassium channels in similar fashion to other known agents such as pinacidil (N-cyano-N'-(4-pyridyl)-N"-(1,2,2-trimethylpropyl)guanidine) and cromakalim ((.+-.)-trans-6-cyano-3,4-dihydro-2,2-dimethyl-4-(2-oxopyrrolid in-1-yl)-2H-1-benzopyran-3-ol). Pinacidil and its analogues are described by H. J. Petersen, et al in J. Med. Chem., 21, 773-781 (1978) and in U.S. Pat. No. 4,057,636. Cromakalim and its analogues are reported by V. A. Ashwood, et al, in J. Med. Chem. 29, 2194-2201, (1986) and in European Patent EP 76-075 B. Pinacidil and cromakalim are considered as standard potassium channel openers against which new compounds are compared. The compounds of the present invention are surprisingly more active at relaxing vascular smooth muscle than either pinacidil or cromakalim.
Since potassium channel openers have been shown to have relaxant activity in several types of smooth muscle, the compounds of this invention will be useful for treatment of hypertension, asthma, incontinence, premature labor, and erectile dysfunction. In addition, based on results with other potassium channel openers, the compounds of this invention will have activity as hair growth stimulants and will be useful for treatment of alopecia.